TeamSixW10 - Module Two

Definitions Worksheet Chapter 3

1. Organic Compound- are complex molecules of life, built on a framework of carbon atoms
2. Inorganic Compound- are considered to be of a mineral not of biological origin.
3. Molecular Formula- is a way of expressing information about the atoms that constitute a particular or chemical bond.
4. Structural Formula- of a chemical compound is a graphical representation of the molecular structure, showing how the atoms are arranged.
5. Isomer- are compounds with the same molecular formula but different structural formulas.
6. Functional Group- a cluster of atoms covalently bonded to a carbon atom of an organic molecule.
7. Condensation (dehydration synthesis) Reaction- two molecules covalently bon into a larger one
8. Hydrolysis (cleavage) Reaction- a molecule splits into two smaller ones (hydrolysis is an example)
9. Monomer- build larger molecules that are the structural and functional parts of cells.
10. Polymer- chains of monomers.
11. Carbohydrates- Organic compounds that consist of carbon, hydrogen and oxygen in a ratio 1:2:1
12. Monosaccharide- simplest forms of sugar.
13. Polysaccharide- are polymeric carbohydrate structures formed of repeating units (mono or di-saccharides) joined together by glycosidic bonds.
14. Lipids- naturally occurring molecules such as fats
15. Saturated Fatty Acid- is fat that consists of triglycerides containing only saturated fatty acids.
16. Unsaturated Fatty Acid- resembles saturated fatty acids except it has one or more double bonds.
17 Protein- are biochemical compounds consisting of one or more polypeptides.
18. Amino Acid- are molecules containing an amine group, carboxylic acid group and a side chain that varies between different amino acids.
19. Denaturation- a structural change in macromolecules caused by extreme conditions.
20. Enzyme- are proteins that catalyze chemical reactions.
21. Hormone- is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism.
22. Nucleic Acid- are biological molecules essential for life, and include DNA and RNA.
23.Purine- is a heterocyclic aromatic organic compound consisting of a pyrimidine ring fused to an imidazole ring.
24.Pyrimidine- is a heterocyclic aromatic organic compound similar to benzene and pyridine.

CHAPTER 3: Basic Introduction to Organic Chemistry
1. ORGANIC COMPOUNDS:
What is an organic compound? Molecules that consist primarily of hydrogen and carbon atoms.
Living things are mainly made out of 3 elements: Oxygen, hydrogen, carbon.
Take away the elements that make up water, what is left? Carbon
What physical and chemical characteristics of carbon make it the leading molecule in living organisms?
a. how many covalent bonds can carbon form with other atoms? 1, 2, 3, or 4 atoms.
b. Can carbon form polar covalent bonds with other atoms? Yes
c. Can carbon form nonpolar covalent bonds with other atoms? Yes
d. What is a carbon backbone? Why is it important that carbon can form a ring, connecting a backbone into a circle? Carbon backbone is when their is a chain of carbon atoms where other atoms can attach. It is important because it means that carbon atoms can be remodeled into a variety of organic compounds.
e. What is a hydrocarbon? Are they hydrophilic or hydrophobic? Water and carbon. Hydrophilic.
f. Make sure you study the different ways of representing carbon-based molecules:

Type of model	Advantage	Limitation
Molecular model	See different characteristics of the same molecule
Structural model	Show how all the atoms in a molecule connect to one another	some atoms or bonds may be implied and not shown.
Ball-and-stick models	Show position of atoms in 3 dimension
Space-filling models	Show how atoms that are sharing electrons overlap
Surface model	Reveals crevices and folds that are important for its function
Ribbon model	Shows all heme groups

2. Functional Groups:
What is a functional group? A cluster of atoms covalently bonded to a carbon atom of an organic molecule.
Why is it important to study the functional groups attached to a carbon backbone on an organic molecule?

Functional group	Character	Location	Water soluble?*	Structure
hydroxyl	Polar	amino acids, sugars, alcohols	yes	-OH
methyl	nonpolar	fatty acids, some amino acids	no	carbon/hydrogen
carbonyl	polar, reactive	sugars, amino acids, nucleotides	yes	carbon/hydrogen/oxygen(aldehyde)
carboxyl	acidic	amino acids, fatty acids, carbohydrates	yes	carbon/hydrogen/oxygen(ionized)
amine	basic	amino acids, some nucleotide bases	yes	nitrogen/hydrogen(ionized)
phosphate	high energy, polar	nucleotides, DNA and RNA, proteins; phospholipids	yes	PO43-
sulfhydryl	forms disulfide bridges	cysteine	yes	disulfide bridges

As a general rule, polar or ionic substances dissolve in polar solvents; nonpolar substances dissolve in nonpolar solvents. As a result, hydrocarbons (being nonpolar) don't dissolve in water. They are often said to be immiscible (literally, "not mixable") in water.
3. Organic molecules can be described as having a simple structure or a complex structure. Those with a simple structure tend to be much smaller in size and serve as “building blocks” (subunits) for making the larger more complex molecules.
A. The smaller subunits are more commonly known as monomers _; and
the larger more complex molecules are known as polymers .
B. The main “building blocks” or subunits of the major biological molecules include the following. (you may need to look ahead in the chapter to find these)
1. SIMPLE sugars_: join together to form complex carbohydrates
2. FATTY acids_: join together with other molecules to form lipids (except for cholesterol and other sterols)
3. Fatty ACIDS: join together to form protein molecules
4._Nucleotides: join together to form nucleic acids

4. Metabolism
What is metabolism? Activities by which cells acquire and use energy as they construct, rearrange and split organic compounds.

Types of metabolic reactions	What happens?
Condensation	Two molecules covalently bonded to form a larger one.
Cleavage (Hydrolysis is an example)	A molecule splits into two smaller ones.
Functional group transfer	A functional group is transfered from one molecule to another.
Electron transfer	Electron are transfered from one molecule to another.
Rearrangement	Juggling of covalent bonds converts one organic compound into another.

D.Hydrolysis : occurs when two monomers combine to form a larger more complex molecule. This type of reaction generally occurs as one monomer loses a hydroxyl group (-OH) while another monomer loses a hydrogen
atom (H) and the two join together to form a molecule of water _. It is for this reason that this type of reaction is also commonly known as a DEHYDRATION SYNTHESIS reaction. The diagram below illustrates this type of reaction

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E Condensation. : occurs when a large complex molecule splits into smaller ones. A common form of this type of reaction is the reverse of a condensation (dehydration) reaction. In this reaction, a molecule of water is used to break a covalent bond. The water breaks apart, adding the Hydrogen atom to one of the monomers and the hydroxyl group to the other monomer. Because water is used to break the bond, this type of reaction is also commonly known as a

clip_image006.jpg

cleavage_ reaction. The diagram below illustrates this type of reaction.

5. CARBOHYDRATES:

These are the most abundant of all the macromolecules found in the biosphere.
Carbon + (2 Hydrogens + Oxygen)n

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Monosaccharide	one sugar unit	vitamin C	glucose
Disaccharide	two sugar units	lactose	sucrose
Oligosaccharide	three or more sugar units
Polysaccharide	hundreds or thousands		cellulose

What type of bond holds sugar subunits together? Backbone of 5 or 6 atoms.
Which type of sugar is part of DNA and RNA? Monosaccharides
There is one simple sugar that the body uses as an energy source and also as a starter material for use in building bigger materials. What is this simple sugar? Glucose
5. Complex Carbohydrates
A. Cellulose
B. Amylose...plants
C. Glycogen...liver...muscles.

Carbohydrate Class

Specific Carbohydrate

Function

Disaccharide (simple sugar)

Sucrose

The most plentiful sugar in nature; also known as table sugar; formed by joining together glucose and fructose

Monosaccharide

glucose

The main energy source for most organisms; serves as building blocks (monomers) for larger carbohydrates

Polysaccharide

Cellulose

Structural material of plant cell walls; formed from long straight chains of glucose; unable to be used by humans as a source of energy; also known as dietary fiber

Monosaccharide

Ribose

Five-carbon sugar found in RNA

Polysaccharide

Glycogen

The complex carbohydrate found in animals, stored especially in liver and muscle tissue; formed from many branched glucose chains

Disaccharide

Lactose

sugar present in milk;formed from glucose and galactose

Polysaccharide

Starch

The storage form for sugars produced by plants using photosynthesis, able to be used by animals as a source of energy

6. LIPIDS:

A. How do you describe lipids?FATTY,OILY OR WAXY ORGANIC COMPAUNDS THAT ARE INSOLUBLE IN WATER.These molecules are greasy or oily to the touch.

B. They are much larger than monosaccharide, contain mostly carbon and hydrogen with much less oxygen than the carbohydrates and therefore are not able to form hydrogen bonds with water. This makes lipids resist dissolving in water or in

other words are (water fearing).

C. These molecules make up about 12-25% of the total body weight.

D. Oils, fats and waxes are all classified as lipids. Oils tend to be smaller in size and liquid at room temperature, fats are larger and are “soft” solids at room temperature, while waxes are much larger and are solids at room temperature.

E. Lipids serve several functions in the body:

1. Reservoire for long-term storage of potential energy_.

2.insulate _ the body (think of whale blubber).

3. Act as a “shock absorber” (padding around sensitive organs like the kidneys) and as space fillers (especially around joints).

4. Are a major part of cell membranes.

5. Some act as hormones (chemical messengers in the body)

F. There are several classes of lipids:

1. fatty acid: have a long hydrocarbon backbone of as any as 36 carbon atoms and a carboxyl group (acid group) attached to the end of the chain (tail). These molecules can be further divided into two main groups:

a. _saturated: those that have all single bonds in the carbon chain, therefore containing the maximum number of hydrogen atoms possible. When something is full, it is saturated (filled to capacity).

b. :unsaturated those that have at least one double bond in the carbon chain, therefore containing less hydrogen atoms than possible without the double bonds. When something is not full, it is unsaturated (not filled to capacity).

Saturated Unsaturated Polyunsaturated

2. Fats(also known as glycerides): these molecules
have one, two or three fatty acid molecules attached to a
glycerol (3 carbon sugar) backbone by a condensation
(dehydration synthesis) reaction. The triglycerides are the
most plentiful lipid found in the body and are stored in
_adipose tissue. Gram for gram, they provide
more than twice the amount of energy when
compared to complex carbohydrates, which is why a high
fat diet tends to cause a person to gain weight. The body
doesn’t use all the energy available, so stores it for later use.
This type of lipid is also used by the body to act as a shock
absorber (padding) to protect organs, and provide thermal insulation. There are several types of fat:
a.Saturated FATS: have fatty acids with all single bonds in the carbon chain. The straight chain allows these molecules to pack tightly together, making it a good form for storage in adipose tissue of animals and causes them to be more solid at room temperature. These molecules tend to be found in animal fat or lard.
b. Unsaturated FATS: have at least one double bond in the carbon chain. The double bond causes the “tail” to bend or kink, keeping these molecules slightly separated from each other. These molecules tend to be easier for the body to digest and less likely to lead to heart or vascular conditions. They tend to be found in plants (olive oil, safflower oil, vegetable oil, etc.).
c. Polyunsaturated FATS: produced by a chemical process called “hydrogenation” where an unsaturated fat (vegetable oil) are forced to accept extra hydrogen atoms, breaking the double bonds to form straight chains. This process causes vegetable oils to pack tightly together, forming a solid at room temperature. They are unhealthy because the body treats them like animal fat.
3. :Phospholipids are similar to triglycerides except that one of the fatty acid tails is replaced with a phosphate group and another very polar group. These groups cause the glycerol portion of the molecule to like
water, so it is often referred to as the _ or polar head. These molecules are the main component of cell membranes that will be discussed in more detail in the next chapter.
4. STEROIDS (STEROLS): this class of lipid does
NOT contain any fatty acid molecules, rather it has
a rigid backbone of four fused-together carbon rings.
Cholesterol is the most common
type found in the body and is modified into various
hormones (estrogen and testosterone), bile salts, as
well as the activated form of vitamin D.
5.Waxes : have very long fatty acid tails that are tightly packed together allowing them to be firm yet pliable. They repel water and therefore act as a good barrier against dehydration and when warmed, serve as a good lubricant. In the ear canal it serves as a sticky covering trapping dust and foreign objects before they reach the ear drum.
6. EICOSANOIDS: these are short chain fatty acid molecules that are released by damaged tissues and function to stimulate nerve endings producing the sensation of “pain”. They are also released by uterus to initiate labor contractions and the secretion of various other hormones.

G. Match the correct lipid below with the their descriptions.
A. saturated fatty acids
B. unsaturated fatty acids
C. saturated triglycerides (fats)
D. unsaturated triglycerides (fats)
E. phospholipids
F. waxes
G. sterols (steroids)
1.C provide the richest source of stored energy for the human body
2 A. these fatty acids have only single bonds between the carbon atoms in the chain with a maximum of hydrogen atoms attached
3.G cholesterol is the most common form of this type of lipid in animal tissues
4 C. have three saturated fatty acid tails attached to a glycerol backbone
5.D vegetable oil is an example of this type of lipid
6.G these type of lipids lack fatty acid tails
7.E these lipids are the main component of cell membranes
8 G. these lipids have a rigid backbone of four fused carbon rings
9.B these lipids have one or more double bonds between the carbon atoms
10.G these lipids are the precursors of vitamin D, fat soluble hormones, and bile salts
11.B butter and lard are examples of this type of lipid
12.D provides insulation from the cold and acts as a shock absorber to protect organs
13.F these lipids provide protection, lubrication and pliability for hair and skin
14.E these lipids have a hydrophilic “head” and two hydrophobic “tails”

7. PROTEINS:

These are the most diverse of all the macromolecules in the body. There are estimated to be more than 140,000 different protein molecules in the body, and they make up more than 50% of the total body weight.
Proteins are macromolecules made from joining together

Amino acids by a condensation (dehydration synthesis) reaction.

A hydrogen atom from the amino group and the hydroxyl
group from the carboxylic acid group form water while the
remaining part of the amino acids form a very strong covalent
bond known as a peptide_ bond.
C. Proteins perform numerous functions in the body:
1. Structural support (especially at the cellular level): within most cells is a cytoskeleton made of protein fibers. (Collagen & Elastin)
2. Movement: muscle contraction is caused by protein fibers sliding against each other. (Actin & Myosin)
3. Transport: especially of substances that do not dissolve in water like fats and most of the oxygen is transported in the blood attached to a protein called hemoglobin. (High & Low Density Lipoproteins: HDL & LDL)
4. Enzymes: protein molecules that help regulate chemical reactions (metabolism) in the body. (Lipase & Protease)
5. Hormones (chemical messengers): released by cells and travel throughout the body signaling cells to modify their activities. (Insulin)
6. Antibodies: one mechanism used by the body for protection against foreign pathogens (disease causing substances or organisms). (Gammaglobulins)
7. Buffering the blood: proteins help to stabilize the pH of the blood.

D. With this many and very different functions to perform, there must be more than one kind of amino acid and proteins must have a very complex structure. When a cell needs to make a protein, enzymes in the cell join together one amino acid after another forming a long chain of amino acids, also known as a
polypeptide chain.
E. There are 20_ different amino acids, however each one
has an amino group (-NH2), a carboxyl or acid group (-COOH)
and one or more atoms called its “R” group (for the “rest” of
the molecule). All three “side groups” are covalently bonded
to a central carbon atom. Each amino acid has only one R group,
but it is the characteristic of the “R Group” that determines the
overall characteristic of each amino acid molecule. The vast
majority of amino acids are neutral, but some are acidic and some
are basic, some are hydrophilic and some are hydrophobic.

F. For each of the following diagrams, circle the “R” group part of the amino acid.

G. The structure of protein molecules is divided into four levels of complexity.
1. Primary_ STRUCTURE: gives the specific sequence (order) of amino acids in the polypeptide chain. In other words, it identifies which of the 20 amino acids is used and in which order they are connected to each other.
a. This structure is stabilized by covalent peptide bonds (very strong covalent bonds) that are difficult to break.
b. If this structure is broken, the protein will fail to function, and the cell will begin to break it down and recycle the amino acids, using them to make new protein molecules. It is not clear why, but this structure can NOT be repaired when damaged; however the cell will reuse the amino acids.
c. Some protein molecules stop at this level of organization. The polypeptide chains arranged in strands or sheets, similar to a rope or sheet of burlap. Proteins with this structural arrangement are common in
muscle, bone, ligaments, and tendons and are called _ proteins.
2.Secondary STRUCTURE: refers to the coiling or “pleating” (sheet-like arrangement) of the protein strand.
a. This structure is stabilized by hydrogen_bonds between the amino group and carboxyl group of amino acids separated by 3 or 4 amino acids.
b. Because these bonds are relatively easy to break, this structure can break and reform repeatedly without damage to the protein chain.
c. This structure allows some proteins to and “elastic” quality or allows the protein to have various forms, kind of like an “ON” and “OFF” form, especially noticed in enzyme activity.
3. Tertiary_ STRUCTURE: refers to the folding of the coiled protein chain on itself forming a three dimensional “ball” or “blob”.
a. This is due to the attraction between some of the “R groups” of the amino acids. Those that are hydrophilic are attracted to each other, and those that are hydrophobic are attracted to each other.
b. Many of the “R groups” have a + or – charge and are therefore attracted to
each other, forming bonds. Once formed, the structure is further stabilized by many additional hydrogen bonds.
c. Because the chance of the exact same + and – ions finding each other a second time is unlikely, if this structure is destroyed, the protein can NOT be repaired, and must be broken down so the amino acids can be used to form other proteins.

4. Quaternary_ STRUCTURE: describes the complex structure that forms as two or more different protein molecules join together. The forces that cause the proteins to join together are the same as those in the tertiary structure, so this structure is also not repairable, but the individual amino acids can be recycled to make new proteins.
a. Hemoglobin (found in red blood cells) is a good example of a protein with a quaternary structure.
b. Lipoproteins (proteins with a lipid molecule attached) and glycoproteins (proteins with a carbohydrate molecule attached) are also classified as quaternary proteins.
c. Proteins with this level of organization are arranged in compact, rounded
shapes (like a “blob”) are commonly called _ proteins. Most enzymes, hormones and transporter molecules in the blood have this structural arrangement.
H.Denaturation is any process that disrupts or destroys the hydrogen bonds or the overall three-dimensional shape of a protein molecule, and thereby changes the overall function of the protein. In most cases the process is irreversible and the protein is destroyed. This process can be caused by changing
the temperature_ or the pH_(acidity) of the cell.
I. Match the following descriptions with the most appropriate term related to proteins and protein structure.

1. K_ amino acid

A coiled or pleated structure caused by regular intervals of hydrogen bonds

2. H_ denaturation

Three or more amino acids joinded in a linear chain

3. I dipeptide

Proteins with oligosaccharides covalently bonded to them

4. C glycoproteins

Folding of a protein molecule due to interactions between the “R” groups of the amino acids in the protein chain

5. E_ lipoproteins

Proteins with cholesterol or phospholipids covalently bonded to them

6. F_ peptide bond

Another name for a covalent bond between two amino acids

7. B polypeptide chain

The globular protein hemoglobin with four protein chains is an example of a protein with this level of organization

8. J_ primary structure

Breaking of protein bonds therby changing the shape and function of the protein

9. G quaternary structure

Formed by joining together two amino acids

10. A secondary structure

The linear arrangement or sequence of amino
acids in a protein molecule

11. D_ tertiary structure

The monomer of all proteins, composed of an amino, phosphate and “R” group.

What causes sickle cell anemia? Explain what happens to produce faulty hemoglobin. What does this say about the importance of the primary structure of a polypeptide being assembled correctly? Inherit two copies of the sickle cell gene. One from each parent. The gene makes abnormal hemoglobin called hemoglobin -S. This abnormal hemoglobin sticks together when it gives its oxygen to tissues. This makes clumps and they cause red blood cells to become stiff and shaped like a sickle. If the primary stuctures of polypeptide isn't assembled correctly it causes a mutation.

8. NUCLEIC ACIDS:
A. These macromolecules are made of “building blocks” (monomers) known as
nucleotides _ that consist of three parts.
1. A five carbon ring_ (ribose or deoxyribose)
2. A phosphate_ group (PO4)
3. A nitrogenousbase (a single or double ring structure that contains a few nitrogen atoms)
a. There are five different nitrogenous bases used to make nucleotides.
(See chapter 13, section 13.2 for details)
1. Two of these are called Purines and have a double ring structure:
_Adenine (A) and Guanine_ (G) found in DNA and RNA
2. Three of them are called Pyrimidines and have a single ring structure: Thymine
(T) and Cytosine_(C) found in DNA
and Uracil(U) only found in RNA

Example of a Pyrimidine Example of a Purine

B. Nucleic acids perform several functions in the body:
1. DNA (deoxyribonucleic acid): stores the genetic information needed for survival.
2. RNA (ribonucleic acid): carries the “working copy” of the genetic information and instructs the production of specific protein molecules.
3. ATP(adenosine triphosphate): the energy form used by cells to drive specific cellular reactions or activities.
4. NAD_ (nicotinamide adenine dinucleotide) and FAD_(flavin adenine dinucleotide): act as coenzymes in metabolic reactions.
5. CAMP_ (cyclic adenosine monophosphate): acts as a chemical messenger within the cell.

C. DNA and RNA structure:
1. These are very large molecules made of many nucleotides connected to each other by strong covalent bonds forming long strands. Since they contain
many nucleotides, they are also called nucleaic acids_.
2. The covalent bonds form between the sugar group of one nucleotide and the phosphate group of the next nucleotide, forming a “backbone” of the molecules with alternating sugar and phosphate groups.
3. RNA is a molecule that has a single_strand of nucleotides.
4. DNA is a molecule that has a double strand of nucleiotides.
a. The sugar-phosphate backbone forms the side chains (like the legs of a ladder)
b. The two “backbones” (legs of the ladder) are connected to each other by
forming _hydrogen bonds between the nitrogenous bases (like the steps on a ladder). Remember that these bonds are weak bonds however when there are many of them working together they are quite strong.

D. Review the structure and function of nucleic acids by matching each of the phrases on the right with a word or phrase from the list on the left. Answers may be used more than once.

_H1. Sugar found in RNA
G 2. Describes the overall structure of DNA_
J3. Short for ribonucleic acid_
D4. Genetic material passed on from parent to offspring_
F5. Nitrogenous bases found in RNA_
B6. Sugar found in DNA_
C7. Nitrogenous bases found in DNA_
D8. Short for deoxyribonucleic acid_
J9. Some act as intermediates that contain protein- building instructions_
I10. Nucleotides contain a 5-carbon sugar, a phosphate group, and a _
A11. The sugar of one nucleotide bonds to the
_of the next nucleotide in the chain, forming the backbone of a nucleic acid.
_ E12. Is a monomer (building block) of nucleic acids

A. Phosphate group
B. Deoxyribose
C. A, T, C, G
D. DNA
E. Nucleotide
F. A, U, C, G
G. Double helix
H. Ribose
I. Nitrogenous base
J. RNA

9. As you have seen in this chapter, there are four main classes of macromolecules. Most are polymers, assembled from smaller monomers (building blocks) in a process called a condensation reaction or dehydration synthesis. Water is produced as a bi-product of these reactions. The process by which the large polymers are broken back down into monomers is called a cleavage reaction or hydrolysis. This process requires that water also be broken down and its parts (the H– and –OH) be used to satisfy the bonds that are broken in the polymer. State whether each of the following statements relates to dehydration synthesis reactions (D) or hydrolysis reactions (H).
1. Connects monomers to form a polymer D
2. Prduces water as a by-product D
3. Breaks up polymers, forming monomers H
4. Water is used to break bonds between monomersH
5. Joins amino acids to form a proteinD
6. Glycerol and fatty acids combine this way to form a fat.D
7. Occurs when polysaccharides are digested to form monosaccharidesH
8. ―H and ―OH groups are removed, forming a water moleculeD
9. Nucleic acid breaks up to form nucleotides.H
10. Water breaks up, forming ―H and ―OH groups on separate monomers.H

Sample Test Questions for Chapter 3 and Lab #7:
1. The four main categories of macromolecules in a cell are

proteins, DNA, RNA and steroids
RNA, DNA, proteins and carbohydrates
monosaccharides, lipids, polysaccharides and proteins
nucleic acids, carbohydrates, monosaccharides and proteins
proteins, nucleic acids, carbohydrates and lipids

2. Of the following molecules, which are the only ones that contain phosphorous?

fatty acids
saccharides
proteins
DNA
all of the above

3. Proteins are built from how many different kinds of amino acids?
a. 4 b. 10 c. 20 d. 30

4. In a hydrolysis reaction, _, and in this process water _.

a polymer breaks up to form monomers…………is consumed
a polymer breaks up to form monomers……….. is produced
a monomer breaks up to form polymers…………is produced
monomers are assembled to produce a polymer…….is consumed
monomers are assembled to produce a polymer……..is produced

5. Proteins are to amino acids as _ are to glucose.

fatty acids
lipids
starches
nucleic acids
monosaccharides

6. When dehydration synthesis takes place what is happening?
a. water has been added to break the polymer into monomers
b. chemical takes up excess hydrogen ions
c. water is removed to link monomers into polymers
d. two amino acids are joining together
e. more than one of the above

7. Lipids are:
a. commonly known as fats
b. hydrophobic
c. molecules that mostly have carbon and hydrogen, very little oxygen
d. include molecules known as triglycerides
e. all of the above
8. TRUE or FALSE: A functional group is generally more reactive than the rest of the molecule.

9. What are the three parts that make up a nucleotide?
a. five carbon sugar, phosphate group, and a double helix
b. phosphate group, nitrogenous base, and a double helix
c. five carbon sugar, nitrogenous base, and enzymes
d. phosphate group, nitrogenous base, and five carbon sugar

10. Which of the following protein structures is (are) reversible?
a. primary
b. secondary
c. tertiary
d. quarternary
e. more than one of the above

11. A molecule with a formula C18H38O is probably a
a. monosaccharide
b. polysaccharide
c. protein
d. fat
e. nucleic acid

12. A major type of lipid found in the cell membrane is
a. steroid
b. triglyceride
c. phospholipid
d. glycerol

13. Peptide bonds
a. hold the polypeptide chains of complex proteins together
b. form between fatty acids
c. are formed by a hydrolysis reaction
d. link amino acids together
e. none of the above

14. What sugar is it that we humans cannot digest?
a. glycogen
b. starch
c. cellulose
d. glucose

15. Depakene 0.75 grams is prescribed by a physician. The bottle of Depakene syrup is labeled 250 mg per 5 ml. How many ml should be given the patient?
a. 1 ml b. 2 ml c. 3 ml d. 5 ml e. 15 ml

CHAPTER 4: Cell Structure and Function
Definition Worksheet #4: Chapter 4
Identify the major function of the following organelles and structures commonly found in cells.
1. Cell membrane A BARRIER THAT SELECTIVELY CONTROLS EXCHANGES BETWEEN THE CELL AND ITS SURROUNDINGS. A MOSAIC OF DIFFERENT KINDS OF LIPIDS AND PROTEINS.
2. Nucleus: Double membraned sac holds a eukaryotic cells DNA.
3. Nucleoulus IN A NUCLEUS, A DENSE, IRREGULARLY SHAPED REGION WHERE RIBOSOMAL SUBUNITS ARE ASSEMBLED.
4. Ribosomes STRUCTURES ON WHICH PROTEINS ARE BUILT, ARE SUSPENDED IN CYTOPLASM.
5. Rough Enoplasmic Reticulum MEMBRANEOUS ORGANELLE,, A CONTINUOUS SYSTEM OF SACS AND TUBES THAT IS AN EXTENTSION OF THE NUCLEAR ENVELOPE . ROUGH ER IS STUDDED.

6. Smooth Endoplasmic Reticulum SMOOTH ER IS NOT STUDDED (LACKS ROBOSOMES)
7. Golgi Body ORGANELLE OF ENDOMEMBRANE SYSTEM ENZYMES INSIDE IT'S MUCH FOLDED MEMBRANE MODIFY POLYPEPTIDE CHAINS AND LIPIDS THE PRODUCTS ARE SORTED AND PACKAGED INTO VESICLES.
8. Vesicles SMALL, MEMBRANE ENCLOSED SAC LIKE ORGANELLE; DIFFERENT KINDS STORE, TRANSPORT, OR DEGRADE THEIR CONTENTS.
9. Lysosomes ENZYME FILLED VESICLE, FUNCTIONS IN A INTRACELLULAR DIGESTION.
10. Peroxisomes ENZYME FILLED VESICLE THAT BREAKS DOWN AMINO ACIDES, FATTY ACIDES, AND TOXIC SUBSTANCES.
11. Mitochondria DOUBLE MEMBRANED ORGANELLE OF ATP FOMATION; SITE OF SECOND AND THIRD STAGES OF AEROBIC RESPIRATION IN EUKARYOTIC
12. Centrioles A BARREL SHAPED STRUCTURE THAT HAS A ROLE IN MICROTUBLE FORMATION IN CILIA, FLAGELLA, AND EUKARYOTIC SPINDLES.
13. Cytoskeleton: microtubules INVOLVED IN THE MOVEMENT OF A CELL OR ITS COMPONENTS; HOLLOW FILAMENT OF TUBULIN SUBUNITS.
14. Cytoskeleton: Intermdediate filaments ARE THE MOST STABLE PARTS OF A CELLS CYTOSKELETON. THEY STRENGTHEN AND MAINTAIN CELL AND TISSUE STRUCTURES.
15. Cytoskeleton: Microfilaments HELPS STRENGTHEN OR CHANGE THE SHAPE OF A CELL.
16. Cilia SHORT MOVABLE STRUCTURE THAT PROJECTS FROOM THE PLASMA MEMBRANE OF CERTAIN EUKARYOTIC CELLS.
17. Flagella LONG, SLENDER CELLULAR STRUCTURED USED FOR MOTION.
18. Tight Cell Junctions LINK CELLS THAT LINE THE SUFACES AND INTERNAL CAVATIED OF AN ANIMALS, THESE JUNCTIONS SEAL THE CELLS TOGETHER SO FLUID CAN'T PASS BETWEEN THEM.
19. Adhering cell junctions ANCHOR CELLS TO EACH OTHER AND TO EXTRA CELLULAR MATRIX' THEY STRENGTHEN CONTRACTILE TISSUES SUCH AS HEART MUSCLE.
20. Gap OPEN CHANNELS THAT CONNECT THE CYTOPLASM OF ADJOINING CELLS. THEY ALLOW ENTIRE REGIONS OF CELLS TO RESPOND TO A SINGLE STIMULUS.

1. General Organization of a Cell:
A. Most cells in the human body have the following three features:
1.PLASMA Membrane( Cell Membrane): forms an outer boundary of
the cell. It has a phospholipid BILAYERarrangement (like an Oreo cookie). The outer surface and inner surface has the phosphate heads that like water
(are HYDROPHILIC ) while the middle of the two layers is made up of the fatty acid tails that
do not like water (are HYDROPHOBIC).
2. Nucleus All eukaryotic cells have this organelle.
a. Please describe its features: Double layer nuclear envelopes, contains DNA, nucleolus here.
b. What is enclosed in the nucleus, necessary for reproduction? DNA
3. :Cytoplasm the space inside the cell between the cell membrane and the nucleus. The space is filled with a semi-fluid liquid called the cytosol and numerous organelles that carry out specific functions.

B. There are two types of cells that will be covered in this class:
1. _Eukaryotic Cells: are those that have a clearly defined nucleus and numerous organelles. Animals and plants that are multicellular organisms have this type of cells.
2. Prokaryotic_ Cells: are those that do NOT have a nucleus (although they do have DNA) and NO organelles. An example would be Bacteria, that are unicellular (1 cell) organisms.
C. What determines the size of a cell?
1. If a cell is too SMALL, there may not be enough space to hold all the organelles needed by the cell to survive.
2. If a cell is too LARGE_, the surface area may not be large enough to keep up with the increased volume, so parts of the cell may not get enough of the needed nutrients from the surrounding environment and will die. Also the cell may not be able to excrete (get rid of) waste products fast enough and the cell will die.
3. As a cell grows, the volume increases faster than the surface area.
a. The formula for Volume of a cell = length x width x height
b. The formula for Surface area of a cell = length x width
c. The volume (cm3) of a cell increases by a power of 3 (cubed) whereas the surface area (cm2) increases by a power of 2 (squared) so the volume increases faster than the surface area as a cell grows in size.

2. Introduction to Microscopes:
A. LIGHT_ Microscope:
1. These were first used around the mid-1600’s
2. This type of microscope uses light to see the sample and lenses to magnify the image seen.
3. These have a maximum magnification of about2,000,000times; beyond that level of magnification the image gets fuzzy or blurry.
4. These microscopes make it is possible to see plant and animal cells, the nucleus, and the largest of the organelles (mitochondria and chloroplasts) as well as most bacteria, but NOT viruses.
5. This type of microscope is the best choice for studying living cells.
B. ELECTRON Microscope:
1. These were first used around the mid-1950’s
2. This type of microscope uses a beam of electrons to create an image that is captured by receptors and stored on a monitor or computer screen.
3. These have a maximum magnification of about 1,000,000_ times.
4. These microscopes make it possible to see even the smallest organelles, viruses and macromolecules like DNA and proteins.
5. A limitation to this type of microscope is that the sample must be frozen, and held in a vacuum. In other words the sample must be DEAD!
6. There are two types of electron microscopes:
a. TRANSMISSION Electron Microscope:
This microscope works by passing a stream of electrons through the slide
and specimen to show internal details of cell structure.
b. Scanning Electron Microscope:
This microscope works by passing a beam of electrons back and forth across the surface of a specimen coated with a very thin layer of metal.
This microscope shows the outer_details of cells, organisms and molecules, providing a three dimensional (3-D) image.

C. Match each description with the correct type of microscope.

1. compound light microscope Bscanning electron microscope C transmission electron microscope A

A narrow beam of electrons pass through a cell to form an image of internal structures.

Glass lenses bend light rays to form an enlarged image of a specimen.

A narrow beam of electrons moves back and forth across the surface of a specimen coated with a thin layer of metal creating an image of external structures.

D. Identify which type of microscope would best be used in each of the following situations.

1. examining the fine structural details within cell organelles

A. compound light microscope

2. observing how a cell changes shape as it moves

B. scanning electron microscope

3. studying the tiny bumps on the surface of a cell or virus

C. transmitting electron microscope

4. filming changes in the nucleus as a cell prepares to divide

A

3. Introduction to PROKARYOTIC Cells: (Bacteria)
A. These cells are structurally the simplest cells known to exist.
B. These cells lack a clearly defined, membrane bound nucleus; the DNA is simply
found in an area called the nucleoid_ region.
C. The CELL membrane (plasma membrane) is selectively permeable and regulates or monitors what gets into and out of the cell.
D. The CELL _ capsule (seen in some of these cells) helps to maintain the shape of the cell and provides added protection.

Many of these cells have a sticky, jellylike coating made of polysaccharides

called a capsule that helps them attach and stick to surfaces.
F. Pili_ (singular: pilus) are short, hair-like extensions that help these cells cling to surfaces or in other words anchor bacteria to surfaces.
G. Cilia_ are longer hair-like extensions used for movement.

4. Introduction to EUKARYOTIC Cells:
A. These cells are structurally much more complex than prokaryotic cells.
B. These cells have a clearly defined, membrane bound nuclei that stores and protects the DNA.
C. The CELL membrane_ (plasma membrane) is selectively permeable and regulates or monitors what gets into and out of the cell.
D. These cells contain other membrane bound sacs called organelles_, each with a specific structure and function. There are numerous benefits or advantages to having these structures in the cell.
1. Having separate organelles surrounded by their own membranes allows a cell to carry out very different activities at the same time. One organelle may be synthesizing (making) a protein while another organelle may be breaking down proteins.
2. Having organelles also greatly increases the membrane surface area, where chemical reactions frequently occur and allow the cell to maintain the needs of the cell while staying relatively small in size.
5. The following is a list of the main organelles and non-membranous structures commonly found in Eukaryotic cells and a description of their primary functions:

CELL MEMBRANE (
Plasma_ Membrane): outer surface of the cell

1. Is called a plasma membrane because it is rather “fluid-like”, NOT rigid.
2. The membrane is described as being selectively permeable, which means it acts like a gatekeeper, controlling what enters and what exits the cell.
B. Nucleus_: generally found near center of the cell
1. Stores DNA (genetic information).
2. Is surrounded by a membrane similar to the cell membrane but it is a double
membrane, also known as the nuclear envelope_, with small openings (nuclear pores) to allow small molecules to enter and leave easily.
3. It contains chromatin_, which is a total collection of all the DNA molecules, unraveled into long strands and scattered throughout the nucleus with their associated proteins. Each individual strand of DNA is known as a
chromosome_ (humans have 46, 23 from each parent) and it is normally not visible under a microscope unless the cell is preparing to undergo division.
4. It contains one or several darkened areas called a _nucleus (plural = nucleoli ) which is the location where RIBOSOMES are made.

Ribosomes: seen as little dots throughout the cell

1. This is the site of protein synthesis.
2. This organelle makes the _structure of the protein, linking together the correct amino acids in the correct order with very strong covalent bonds called peptide bonds.
3. Some are scattered throughout the cytoplasm and are called “free” whereas others are attached to the surface of other organelles and are called “fixed”.

Those that are “free” produce proteins that remain in the cell cytoplasm.
Those that are “fixed” produce proteins that will become part of the cell membrane or be secreted from the cell to be used by other cells.

Endoplasmic_ RETICULUM (ER): network of interconnected sacs (like a maze) that primarily function as “storage sheds”. There are two types:

1. Rough ER:
a. is generally found near the nucleus (or continuous with it) and has what
appears to be many tiny dots (ribosomes) on the surface when viewed under a transmission electron microscope.
b. the primary function is to begin to
modify the protein structure (forming
the 2o and 3o structures) and storing the
protein made by the ribosomes
c. this organelle begins the process of
forming the proteins that will become
part of the cell (plasma) membrane

2. Smooth _ER:
a. found anywhere in the cell, but does NOT have the dots (ribosomes) on the surface.
b. synthesizes and stores lipids (fats) and
then modifies them into fatty acids,
phospholipids and steroids
c. it makes the lipid molecules that become
part of the cell membrane.
d. in some cells, the smooth ER stores other substances:
- calcium in muscle cells (for help in muscle contractions)
- enzymes in liver cells (for detoxifying blood)
E. TRANSPORT VESICLES: small round “sacs” scattered throughout the cell
that are designed to move substances from one organelle to another (especially from the rER and sER to the Golgi Complex).
F. Golgi BODY (or COMPLEX or APPARATUS): a stack of flattened sacs (like plates) that are NOT connected to each other.
1. This organelle further modifies molecules produced
in the rough and smooth endoplasmic reticulum. For
example a protein or carbohydrate coat may be added
to a lipid molecule, forming a lipoprotein or a glycolipid.
2. As the molecule is “improved”, it moves from one
chamber to the next until it is finally released from the
complex.
G. SECRETORY VESICLES: these are similar to transport vesicles except the final destination is the cell membrane, so the contents can be released (secreted) from the cell, or the membrane of the vesicle can become part of the cell membrane.
H. Lysosomes: these are similar to transport vesicles, but are generally larger in size and they stay inside the cell. These organelles contain enzymes for digesting macromolecules or destroying bacteria that enter the cell, or cell parts (damaged organelles) found within the cell. In a sense, they are like the cells “garbage disposal”.

Peroxisomes: these are also similar to transport vesicles, and they also

stay within the cell. They contain enzymes that break down fatty acids,
amino acids and hydrogen peroxide_(a toxic substance produced by the metabolism of some proteins and fatty acids). These organelles are found in a higher number in liver and kidney cells where their primary
function is to break down alcohol and other toxins (drugs).

J. Mitochondria: a kidney bean shaped organelle with an inner chamber that has a large surface area by folding in on itself forming finger-like projections called cristae.
1. This organelle is the site of energy production.
as it converts glucose into ATP .
2. There may be several of them depending on the
energy demands of the cell.
K. Vacuoles: small “sacs” that store water or food substances. These are not so clearly visible in animal cells, however because plants can not relocate to find water, they tend to have a very large, central vacuole for water storage.
L. CYTOSKELETON: a network of protein fibers of various sizes, scattered throughout the cell cytoplasm.
1. Microfilaments: these are the smallest of the fibers and are typically found just under the surface of the cell membrane forming the cell cortex and reinforce the membrane. It helps with maintaining and changing the shape of a cell.
2. Intermediate FILAMENTS: as the name implies are in between in size. These are scattered throughout the cytoplasm (like a net) and help to stabilize the cell as well as helping organelles remain in position (especially the nucleus).
3.Mircrotubules : these are the largest of the fibers and providing rigidity to the cell, and form “tracks” for organelles to follow as they move about inside the cell
M. _Flagella: long extensions from the cell membrane, generally few in number, that acts like a “tail” or “whip” and moves the cell in the surrounding area. The sperm cell is the only cell in the human that has this structure.
N. _Cilia: short “hair-like” structures on the surface of the cell and are responsible for moving substances along the surface of the cell (out with old, in with new). The cells that line the respiratory tract and fallopian tubes (in women) have many of these structures.
7. Circle one of two possible answers given between the parentheses in each statement.
1. ( Protein Carbohydrate ) subunits form the basic components of microtubules.
2. ( Microtubules Microfilaments ) mechanically supports cell membrane and helps
the cell change its shape.
3. Sperm and many other free-living cells use ( flagella cilia ) as whip-like tails for movement from one location to another.
4. The human respiratory tract is lined with beating ( flagella cilia ).

8. Review the various organelles by matching each phrase on the right with a structure from the list on the left. Answers can be used more than once and some require more than one answer.

A. Nucleus
B. Transport vesicle
C. Secretory vesicle
D. Smooth ER
E. Lysosome
F. Golgi apparatus
G. Rough ER
H. Fixed Ribosomes
I. Free Ribosomes
J. Peroxisomes
K. Mitochondria

D 1. Lipids are manufactured, modified or stored here
I 2. Forms the primary structure of a protein molecule that is probably going to be used by the cell
A 3. Contains chromatin
E 4. Contain enzymes that break down large molecules or pathogens, or in other words carry out intracellular digestion
C 5. Carries secretions for export from cell
J 6. Breaks down drugs and alcohol in liver
D 7. Makes the phospholipid part of cell membranes
A 8. Cell control center
_ 9. Numerous ribosomes on its surface give it its name
F 10. Performs the final modifications of substances that will become part of the plasma membrane or other organelles, or be exported outside the cell
B 11. Deliver proteins, lipids and other substances from the ER to Golgi apparatus
C 12. Buds off from the Golgi apparatus and migrates to the cell membrane
H 13. Forms the primary structure of proteins that are probably going to be secreted from the cell
K 14. Acts like the “power plant” for the cell, producing large amounts of ATP
F 15. Takes in transport vesicles from the ER and performs the final modification of their contents
A 16. Surrounded by a double layer membrane with pores, often called an “envelope”

9. One more time, match each phrase with a structure from the list on the right. Answers can be used more than once and some require more than one answer.

1. I Assembles the primary structure of polypeptide chains
2. A Assembles and stores lipids in the cell
3. B Stores and protects the DNA instructions for building polypeptide chains
4. H Initiates protein modification following assembly of polypeptide chains
5. C Location where proteins and lipids take on their final form
6. G Process that transport substances out of the cell cytoplasm
7. F Process that transports substances into the cell cytoplasm
8. L Special vesicles budding from the Golgi body that contain enzymes that break down fatty acids and amino acids, forming hydrogen peroxide
9. K Special vesicles budding from the Golgi body that become organelles of intracellular digestion
10. E Transport unfinished proteins to the Golgi body for final modification
11. D Transport finished cellular products to the plasma membrane for export from the cell
12. C Sorts and packages lipids and proteins for transport to their proper destinations following modification
13. J Transport unfinished lipids to the Golgi body for final modification

A. spaces within the smooth membranes of ER
B. nucleus
C. Golgi body
D. vesicles budding from the Golgi body
E. vesicles budding from the rough ER
F. endocytosis with vesicles
G. exocytosis with vesicles
H. spaces within rough ER
I. ribosomes in the cytoplasm
J. vesicles budding from smooth ER
K. lysosomes
L. peroxisomes

10. The ENDOMEMBRANE SYSTEM:
Some of the organelles mentioned are closely connected to each other forming a “pathway” from the center of the cell to the surface for secreting products made within the cell, and replacing or expanding the cell membrane, or in some cases for creating storage areas for enzymes and molecules (lysosomes, peroxisomes and vacuoles). To be a member of this system, the structure must have a membrane and must be part of the pathway; just having a membrane is not enough!
A. Included in the endomembrane system, in their correct order from inside out:
Smooth and Rough ENDOPLASMIC RETICULUM, TRANSPORT VESICLES, GOLGI COMPLEX, SECRETORY VESICLES, CELL MEMBRANE, (also the LYSOSOMES, PEROXISOMES and VACUOLES if they are not producing a substance to be released from the cell).
B. Not included in the endomembrane system:
RIBOSOMES (because they do not have a membrane) and
MITOCHONDRIA (because it is not synthesizing or modifying a substance to be exported or used by the cell)

11. CELL JUNCTIONS: connections that hold cells in close proximity to each other

Tight_ JUNCTIONS: bind cells together forming a leak-proof barrier, preventing substances from sliding between the cells, kind of like a zipper, (seen in the stomach and intestinal lining)

B. _Adhering (Anchoring) JUNCTIONS: anchor cells together and to surfaces (like a “spot weld” or roots of a tree in the ground) protein fibers attach to the cytoskeleton inside the cell membrane.
C. Gap_ (Communicating) JUNCTIONS: canals (openings) in the cell membrane that allow cells to function as a unit.

12. Choose the most appropriate description for each type of junction.

1. C_ adhering or anchoring junctions
2. B_ gap or
communicating junctions
3. A_ tight junctions

A. Link the cells of epithelial tissues lining the body’s outer surface, inner cavities, and organs to prevent substances from “leaking” between the cells.
B. Link the cytoplasm of neighboring cells, forming an opening for cellular contents to move back and forth freely between the cells.
C. Link the cells in tissues of the skin, heart, and other organs that are subject to stretching, holding them firmly together.

Sample Test Questions for Chapter 4 and Lab #8:

1. Which of the following clues would help you identify if a cell is a prokaryotic or eukaryotic cell?

the presence of a rigid cell wall
the cell contains DNA
the cell carries out cellular metabolism
the cell has a clearly defined nucleus
all of the above

2. True or False: The nucleus is located in the cytoplasm.

3. Which of the following is not part of the endomembrane system?

Secretory Vesicle
Golgi apparatus (complex)
Smooth Endoplasmic Reticulum
Rough Endoplasmic Reticulum
Mitochondria

4. Most of the protein used by a cell is produced in the

Ribosomes
Smooth endoplasmic reticulum
Nucleus
Mitochondria
Golgi apparatus (complex)

5. Cellular organelles and structures seen in the cell can be divided into specific groups based on their functions. Which of the following is a function carried out by acellular organelle or structure?

manufacture large molecules from smaller fragments
break down large molecules into smaller fragments
produce ATP for energy
allow for movement of the cell
all of the above are functions performed by organelles

6. You would expect a cell with a large amount of smooth endoplasmic reticulum to

make a lot of lipids
move about actively in it’s surroundings
secrete a lot of protein from the cell
produce a large amount of ATP for energy

7. It is essential for skin cells to remain tightly bound to each other to maintain the integrity of the skin. The cell junctions that would best allow this are called

anchoring (adhering) junctions
tight junctions
communicating (gap) junctions

8. Most hormones are proteins that are secreted into the bloodstream to help activities in the body. Which of the following best describes the correct order of organelles the hormone might pass through from its production to its exit from the cell? (not all structures are listed)

rough ER, transport vesicle, Golgi apparatus, ribosomes, cell membrane
smooth ER, ribosomes, transport vesicle, Golgi apparatus, lysosome, cell membrane
ribosomes, rough ER, transport vesicle, Golgi apparatus, secretory vesicle, cell membrane
ribosome, smooth ER, Golgi apparatus, transport vesicle, lysosome, cell membrane
rough ER, ribosomes, Golgi apparatus, transport vesicle, cell membrane

9. The ribosomes are formed by the

rough endoplasmic reticulum
smooth endoplasmic reticulum
Golgi apparatus
Mitochondria
Nucleoli

10. TRUE or FALSE: As a cell grows in size, the surface area increases at the same rate as the volume of the cell.

11. TRUE or FALSE: On a light microscope, the shortest ocular has the lowest (smallest) power of magnification.

12. A scientist wants to magnify a pollen grain 5000 times to better examine the organelles inside the cell. Which of the following microscopes would be best to use in this situation?

light microscope
scanning electron microscope
transmission electron microscope
all of the above

13. When working with a microscope, if the slide is moved to the right and away from you, how will the image viewed through the eye piece move?
a. to the right and away from you
b. to the left and away from you
c. to the right and toward you
d. to the left and toward you

CHAPTER 5: Organization of the Cell Membrane
1. Cell Membrane Structure:
A. There are many different molecules including, phospholipids, glycolipids, cholesterol, proteins and glycoproteins in the cell membrane. This is why the membrane is often described as having a “mosaic” appearance.
B. The most abundant part of the cell membrane is phospholipids_ molecules that are arranged in two layers.
1. The central portion is composed of fatty acid tails and cholesterol and is
therefore “water fearing” (hyrophobic or non-polar)
2. The outer and inner surfaces have the “head” of the phospholipid molecules that contain a glycerol backbone (sugar), a phosphate group and hydroxyl
groups that are all “water loving” (Hydrophilic or polar)
C. The unsaturated phospholipid tails of the membrane have a slight bend that helps to keep the molecules from packing too tightly together, and helps keep it more “fluid-like”.
D. The lipid molecule cholesterol is more rigid and helps to stabilize the “fluid-like” phospholipid bilayer at normal body temperature providing some stability and rigidity to the membrane.
E. The many different protein molecules that are part of the cell membrane have just as many different functions (described below).
F. The membrane is described as being SELECTIVELY PERMEABLE, which means that some substances may cross the membrane easily, some must pass through special protein channels, and still others may not cross at all.
1. non-polar or lipid soluble molecules cross directly through the phospholipid part of the membrane easily
2. polar or water soluble molecules can only cross through specific protein channels found in the phospholipid membrane
G. The cell membrane is originally produced at the endoplasmic reticulum, portions “bud-off” to become transport vesicles that move to the Golgi body, where the protein molecules are further modified. Secretory vesicles then move to the cell membrane and fused with it in a process called exocytosis.
2. The membrane proteins serve several different functions. Some of these were introduced in chapter four.
A. ANCHORING or Adhesion_ Proteins: help cells of the same type stick together to form tissues. They serve as attachment points for the phospholipid membrane to the internal cytoskeleton and external fibers, or to neighboring cells. These are typically found in tissues that must be able to stretch as an organ fills, such as in the walls of the stomach, heart, and urinary bladder.
B. COMMUNICATING or Gap Junction Proteins: form an open channel between two cells allowing chemicals and “messages” to pass quickly from cell to cell so they may function more effectively as a group. These are expecially common in the walls of the heart.

C. Recognition Proteins: serve as a kind of “identification tag” for a cell, allowing antibodies and white blood cells to detect who “belongs” and who must be “destroyed” because they do not belong in the body. These also are responsible for the various blood types (A, B, AB, etc.)
D. Receptor_ Proteins: serve as binding sites for signaling molecules (hormones) that will trigger a change in the activities of the cell. This is why some cells respond to a specific chemical (hormone) while others do not.
E. ENZYME Proteins: assist the cell by speeding up essential chemical reactions. They are generally found attached to either the outer or inner surface of the membrane.
F.Transport Proteins: help move water and water soluble (polar) substances across the phospholipids membrane. These protein molecules have an internal channel and tend to be very specific (selective) for the substance moving through them. There are two main types of these proteins:
1. Passive Transporters: do not require energy for activation
2.Active Transporters: do require energy for activation
3. There are several “driving forces” that influence the movement of substances across the cell membrane:
A.Concentration of a Solution: this is defined as the density of a
particular substance in a given area (volume). is defined as the comparative solute concentration of two solutions on either side of a selectively permeable membrane.
1. There are essentially three “types” of solutions when discussing the movement of substances across a membrane:
a. Hypertonic SOLUTION (“strong”): one with a high concentration of solutes, therefore one with relatively less water.
b. Hypotonic SOLUTION (“weak”): one with a low concentration of solutes, therefore one with relatively more water.
c.Isotonic _ SOLUTIONS: those where the concentration of solutes is the same on both sides of the membrane, therefore the relative amount of water is the same also.
2. Because the cell membrane is selectively permeable, there is a tendency for some molecules to have a greater concentration on one side of the membrane than the other. The composition of the intracellular fluid is quite different from the composition of the extracellular fluid surrounding the cells in the body. For most cells in the body, there is a higher concentration of protein molecules, ATP and potassium ions (K+1) inside the cell than outside the cell. There is also a higher concentration of everything else outside the cell, especially sodium ions (Na+1) and chloride ions (Cl-1).

3. The difference in composition on each side of a cell membrane is called a concentration
GRADIENT. There is a natural tendency for
molecules to move away from the side of the membrane with a high
concentration and towards the side of the membrane with a low concentration (DOWN their concentration gradient) if at all possible.
B. Because there are many ions in solution, one side of the membrane will often be more positive and one side more negative, which creates an unequal charge distribution. Thcharge differences also tend to influence the movement of ions across the membrane. Remember that ions that have the same charge tend to repel
each other while those with opposite charges tend to
_attract each other. Differences in electrical charges on each side of
a cell membrane is called an ELECTRICAL Gradient _.
C. Because there are numerous gases dissolved in the body (especially O2 and CO2) there is typically a gradient that influences the movement of gases across membranes throughout the body, especially between the lungs and the blood vessels within the lungs. As the concentration of a gas in solution increases, so does the pressure of the gas. Differences in gas pressure on each side of a
membrane is called a _Pressure GRADIENT.
4. Substances move across a cell membrane by two main processes:
A. ACTIVE TRANSPORT involves the movement of molecules or ions across a
membrane from the side with a lower_ concentration to the side with
a higher concentration. In other words, the molecules are moving
against_ their concentration gradients. This process requires that the cell use energy (ATP) to accomplish this action and the substance is described as being “pumped” across the membrane.
1. If the transporter protein “pumps” two substances at the same time and in the same direction, they are called SYMPORTERS.
2. If the transporter protein “pumps” two substances at the same time in opposite directions, they are called ANTIPORTERS. The most common example of this type is the sodium-potassium pump (found in nerve and muscle cells).
B. PASSIVE TRANSPORT involves the movement of molecules and ions across a
membrane from the side with a higher_concentration to the side with a
lower_ concentration, or in other words, the molecules are moving
toward their concentration or pressure gradients. This process does not
need the cell to supply additional energy_ (ATP) to move the substance across the membrane.

5. There are three main mechanisms that use the passive transport process:
A. Diffusion : the natural tendency for particles to spread out from an area of high concentration to an area of low concentration.
1. Remember that the cell membrane is selectively permeable. Lipid soluble
( non-polar or hydrophobic) molecules can pass directly through the cell membrane as though it is not there. This is also how fat soluble vitamins and dissolved gases like oxygen (O2) and carbon dioxide (CO2) cross the cell membrane.
2. There are several factors that will increase diffusion rates across cell membranes or other membranes in the body:
a. Greater the difference in concentration of solutes on each side of the
membrane,the higher the rate of diffusion
b. Warmer the temperature of a solution, the afaster molecules are moving about in the solution
c. Larger the size of the molecules, the slower they move
d. Ions of opposite charges (+ and -) attract each other, whereas
those that have the same charges repel each other.
e. An increase in pressure of a gas on one side of a membrane causes molecules to try to move to an area with less pressure.
f. Larger surface area available for diffusion will increase the rate of diffusion. This is especially important in the lungs and intestines.
g. The shorter the distance to diffuse, the faster diffusion occurs. This doesn’t apply to cell membranes as they are all the same thickness (phospholipid bi-layer), however when the lungs fill with fluid, it is harder for the oxygen to diffuse into the blood because it must move through the liquid as well as through the membrane.
B.Facilitated DIFFUSION: the movement of water molecules
and water soluble (polar or hydrophilic_) particles from the side of a selectively permeable membrane with a higher concentration of the molecule that is moving to the other side with the assistance (help) of a membrane protein.
1. Some of these protein channels are always open (leakage channels), but only allow specific molecules to pass through. Many animal and plant cells have
channels called aquaporins that are always open and allow water to cross the membrane easily to help maintain a proper fluid balance.
2. Some channels must change their shape to allow a molecule to pass through and therefore can regulate when and if a substance gets through
or not. These proteins are said to be “gated” and can open or close in response to stimuli like a specific chemical, pressure or changes in membrane electrical gradients.

C.osmosis : the diffusion of water across a selectively permeable
membrane. Water like any other substance diffuses from an area of _higher
water concentration to an area of lower water concentration.
1. The direction of movement of water across a membrane is sometimes difficult to keep straight because solutions are described by the concentration (amount) of the solutes dissolved in the water, not by the amount of the water.
2. Water molecules move across a selectively permeable membrane from the
solution that is hypo TONIC to the solution that is hyperTONIC. A hypotonic solution has relatively more water compared to a hypertonic solution, and water moves from the solution where there is “more of it” to the solution where there is “less of it”.

Hypotonic Hypertonic Isotonic
Solution Solution Solution

6. There area several additional forces that influence the movement of WATER across membranes:
A. hydrostatic PRESSURE: is the force generated by the flow of a fluid against a membrane. In the circulatory system the heart pumps blood, which when under pressure tends to push the fluid through openings in membranes, carrying with it all small substances dissolved in the blood. This is the driving force behind how the kidneys filter the blood
B.osmotic PRESSURE: is the force needed to prevent water from flowing across a membrane, down the concentration gradient for the water. This is the driving force behind how the capillaries (very small blood vessels) “pull” tissue fluid back into the circulatory system.

7. There are several process that are used to move large quantities of substances or molecules or substances that are too “large” to cross the cell membrane through the protein channels:
A. exocytosis_: this is the process the cell uses to expel or export large molecules produced inside the cell. Transport vesicles fuse with the membrane and the contents “spill out” of the cell. This is also the way the membrane is replaced with a “new and improved” membrane each time a substance is exported from the cell.

B.endocytosis _: this is the process the cell uses to take in large molecules for use by the cell or to be destroyed by the cell in the case of white blood cells. This is also the way worn-out membrane is repaired by the cell as sections are pulled into the cell and broken down by fusing with lysosomes. .

There are three basic forms of Endocytosis:
1. receptor-mediated_ ENDOCYTOSIS: receptors on the surface of the cell membrane bind to very specific substances (hormone, vitamin, mineral, etc.), then the membrane folds in on itself forming a vesicle.
2. phagocytosis_: this is the process the cell uses to “engulf” large microorganisms or “food particles” that happen to be in the extracellular fluid. This process is also thought of as “cellular eating”
3.bulk-phase ENDOCYTOSIS: this process is much less selective and is used primarily to remove excess membrane that forms as exocytosis occurs, or to remove sections of worn-out membrane. This process is sometimes known as PINOCYTOSIS or is thought of as “cellular drinking”, as some of the extracellular fluid is brought into the cell in the process.

8. Hydrophilic (polar) substances cross the cell membrane with the assistance of transport proteins. For each of the following, choose one of the mechanisms of protein-mediated transport listed. Some descriptions below require active transport, some indicate passive transport is required, while other descriptions do not provide enough information to definitively chose one or the other, so may apply to either active or passive transport.
A. active transport
B. passive transport
C. may apply to either active or passive transport
1.A. The calcium channel pump uses this method to transport calcium
2.B. The transport protein channel changes shape
3.B. Involves a transport protein that is not energized
4.B. A transport protein is specific to only one type of substance
5.A. Solute molecules move across the membrane from the side with a higher concentration to the side with a lower concentration of the solute molecule
6.A. The transport protein must receive an energy boost, usually from ATP.
7.A. Binding of ATP to a transporter protein leads to changes in protein shape
8.B. Net movement of solutes will be down the solute’s concentration gradient using this method of transport.
10.A. A solute is pumped across the cell membrane against its concentration gradient.
11.A. The solute binding site improves when ATP donates energy to the transport protein to allow a better chemical fit.
12.B. Passive two-way transport will continue until solute concentrations become equal on both sides of the membrane.

A. The sodium-potassium pump uses this mechanism of transport
9.

9. Osmosis is an important process that has many effects on living things. Test your understanding of osmosis by predicting in each of the following cases whether water will enter the cell (In) or leave the cell (Out), or whether there will be no net movement of water (None). Assume that the plasma membrane is permeable to water but not to the solutes.

OUT 1. A cell is exposed to a hypertonic solution.
OUT 2. A cell is placed in a salt solution whose concentration is greater than that of the cell contents.
IN 3. Due to disease, the solute concentration of the body fluid outside the cell is less than the solute concentration of the cytoplasm.
NONE 4. The cell is in an isotonic solution.
IN 5. A single-celled organism is placed in drop of pure water for examination under microscope.
OUT 6. A cell is immersed in solution of sucrose and glucose whose combined concentration is greater than the concentration of solutes in the cytoplasm.
IN 7. The solute concentration of the cell cytoplasm is greater than the solute concentration of fluid surrounding the cell.
IN 8. A cell is exposed to a hypotonic solution.
NONE 9. The concentration of solutes in the cytoplasm is equal to the solute concentration of the extracellular fluid.
OUT10. The cytoplasm of a cell is more dilute than the surrounding solution

10. Choose the most appropriate answer for each.

1. C. bulk flow
2. F. osmosis
3. A. tonicity
4. H. hypotonic solution
5. E. hypertonic solution
6. B. isotonic solutions
7. I. hydrostatic pressure
8. D. osmotic pressure
9. G. plasmolysis

A. Refers to the relative solute concentrations of two fluids
B. Having the same solute concentrations
C. Mass movement of one or more substances in response to pressure, gravity, or other external force
D. The amount of force that prevents further increase in a solution’s volume
E. The fluid on one side of a membrane that contains more solutes than the fluid on the other side of the membrane
F. The diffusion of water in response to a water concentration gradient between two regions separated by a selectively permeable membrane
G. Osmotically induced swellingh of a cell until it ruptures
H. The fluid on one side of a membrane that contains fewer solutes than the fluid on the other side of the membrane
I. A fluid force exerted against a cell wall and/or membrane enclosing the fluid

11. If the statement is true, write a T in the blank. If the statement is false, make it correct by changing the underlined word(s) and writing the correct word(s) in the answer blank.

T 1. Because membrane exhibits selective permeability, concentrations of dissolved substances can increase on one side of the membrane or the other.
T 2. A water concentration gradient is influenced by the number of solute molecules present on both sides of the membrane.
T 3. The relative concentrations of solutes in two fluids are referred to as tonicity.
F 4. An animal cell placed in a hypertonic solution would swell and perhaps burst.
F 5. Physiological saline is 0.9 percent NaCl; red blood cells placed in such a solution will not gain or lose water; therefore, one could state that the fluid in red blood cells is hypertonic.
F 6. A solution of 80 percent water, 20 percent solute is more concentrated than a solution of 70 percent water, 30 percent solute.
T 7. The mass movement of one or more substances in response to pressure, gravity, or some other external force is called osmosis.
T 8. Animal cells placed in a hypotonic solution will swell.
12. Review the function of cell membranes by matching each of the phrases on the right with the appropriate mechanisms from the list on the left. Answers may be used more than once and some questions require more than one answer.

A. Diffusion
B. Active transport
C. Osmosis
D. Phagocytosis
E. Passive transport
F. Facilitated diffusion
G. Pinocytosis
H. Receptor-mediated endocytosis
I. Exocytosis

A,E 1. Movement of substances across a biological membrane directly through the phospholipids bilayer
B 2. Moves solutes against concentration gradient
E,F,A 3. Any spread of molecules from area of higher concentration to area of lower concentration
F 4. Movement of substances across a membrane down the concentration gradient with the help of a transport protein
H,O,G 5. Three types of endocytosis where substances enter the cell and are contained within vesicles.
G 6. Engulfing of fluid in membrane vesicles
C 7. Diffusion of water across selectively permeable membrane, from hypotonic to hypertonic solution
B 8. Transport molecules use ATP to function better
H 9. Enables cell to engulf bulk quantities of very specific large molecules that bind to surface proteins
A 10. How oxygen and carbon dioxide enter and leave cells
F,C 11. Two examples of passive transport through a protein channel in the membrane
D 12. Engulfing of large particle in membrane vesicle
I 13. Fusion of membrane-bound vesicle with membrane, and dumping of contents outside cell
D 14. How a cell might capture a bacterium
E,F15. A general term used to represent the movement of substances down their concentration gradient through a protein channel without the use of ATP energy.

Sample Test Questions for Chapter 5:

1. The cell membrane consists mostly of a

a. _: consist of TWO sugar molecules. Examples include:
1. Sucrose (also known as table sugar) which consists of a glucose molecule bonded to a fructose molecule
2. Lactose (also known as milk sugar) which consists of a glucose bonded to a galactose molecule

3. Maltose (also known as grain sugar) which consists of two glucose molecules bonded to each other
b. _: consist of a FEW sugar molecules (the word few is a very vague term meaning more than two but less than many). These are found on the surface of cells and serve as antigens (cell markers) as in determining blood type (A, B, AB or O).
3.

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